Abstract
Brain activity in the moments leading up to successful verbal recall provide a window into the cognitive processes underlying memory retrieval. But these same recordings also subsume neural signals unrelated to mnemonic retrieval, such as response-related motor activity. Here we examined spectral EEG biomarkers of successful recall under an extreme manipulation of mnemonic demands: subjects either recalled items after a few seconds or several days. This manipulation isolated EEG components specifically related to episodic retrieval. Theta and gamma power (4-8 Hz and 40-128 Hz respectively) increased immediately prior to long-delay recall, whereas 8-20 Hz power decreased. A direct comparison of long-delay and immediate recall revealed a nearly identical pattern, indicating that these spectral biomarkers of successful retrieval reflect memory-specific processes. Ruling out a confound of motor related activity, these results identify theta and gamma activity as biomarkers of successful episodic memory retrieval.
Competing Interest Statement
The authors have declared no competing interest.